The basic objective is to develop normal human bladder epithelial cell lines for studies on the mechanism of chemical carcinogenesis. To achieve this goal, culture methods and nutrient media will be designed for this specific cell type. The epithelial nature and normality of isolated cell lines will be established by morphological, ultrastructural, chromosomal and functional properties. Transformation criteria for epithelial cells will be investigated since these differ from those useful for fibroblasts. For system development, direct-acting bladder carcinogens will be employed. The role of promoters, inhibitors and nutritional factors in bladder carcinogenesis will be investigated after the system has been developed and characterized. Although most human cancers are derived from epithelium, most model culture systems are fibroblastic. The system we propose to develop will make it possible to study the action of chemical carcinogens in the appropriate target cell.